This invention relates to systems for use in orienting an object and to systems and processes relating to the generation and/or use of reference signals which bear directional information.
Many systems for orienting the direction of an object in a plane of general movement therefore depend upon the earth's magnetic field to provide the reference direction that serves as the basis for determining the necessary adjustments to the direction of the object. While generally useful, the magnetic field of the earth is known to vary and change in certain areas of the world so that such use of the magnetic field to provide a directional reference has its limitations.
Apart from the variances in the earth's magnetic field in difference locals, the earth's magnetic field is distorted in highly populated areas where the ever present steel structures act as magnetic shields that serve to collapse and/or distort the local magnetic field. As such, magnetic compass bearings in such areas are unreliable so that directional bearings which are taken by magnetic compasses provide a poor reference source for use in orienting the direction of an object.
Within buildings that have a skeletal steel structure, and in storage areas where steel or other field collapsing items are stored, the use of the earth's magnetic field as a directional reference for the automatic orientation of objects is also impractical. In such places, the automatic directional orientation of objects is frequently accomplished by procedures that involve the sensing of painted strips and other objects, which have a fixed location and, accordingly, have a capability of serving as a reference for automated object movements in the area.
As such, there is a need for a signal that may be used to provide a directional reference in areas where the direction indicated by the earth's magnetic field is unreliable and particularly in areas where the field is distorted by local items and materials that serve as a magnetic shields or drawing points for the earth's magnetic lines of force. In addition there is a general need for systems which provide for the appropriate generation of such signals and facilitate the angular directional orientation of objects through the use thereof.